In recent years, touch panels serving as input devices are gradually applied to various electronic devices such as mobile phones, personal digital assistants (PDAs), and tablet personal computers (tablet PC). When a touch panel serves as an input device, several operation approaches can be applied for instructing an electronic device to perform various operations. For example, sliding on the touch panel means moving, tapping the touch panel once means clicking a left mouse button, tapping the touch panel twice means clicking a right mouse button, and tapping and sliding on the touch panel means dragging. However, in order to perform the foregoing operation approaches smoothly, a touched position at each of time points needs to be accurately detected on the touch panel so that which operation approach is to be performed can be determined. For example, a direction and a distance are determined according to touched positions at successive time points when sliding is performed on the touch panel.
In addition, the touch panel is often used in a portable electronic device, thus making power consumption of the touch panel being an important factor that affects efficiency of the electronic device.